To overcome the lack of effectiveness of existing treatments against whooping cough, French scientists have developed a nasal spray vaccine to limit the spread of respiratory bacterial infection.
- A nasal vaccine mimics the modes of transmission and colonization of the bacterium Bordetella pertussis, responsible for whooping cough, in the mucous membranes of the respiratory tract.
- According to a phase 2 clinical trial, a single nasal administration induced strong and long-lasting immunity in the nasal mucosa in addition to blood immunity.
- “No serious vaccine-related adverse events” were reported.
It has long been mistakenly considered a disease of infancy. Pertussis is a highly contagious respiratory infection caused by bacteria Bordetella pertussis, which can be severe at any age. It can become serious, even fatal, for pregnant women, the elderly and babies under six months old. This pathology, whose contamination is by air in contact with a sick person, is treated with antibiotics from the macrolide family.
BPZE1: a nasal vaccine mimicking “modes of transmission and colonization”
Pertussis can be prevented through vaccination, which has been mandatory for infants since January 1, 2018, according to health insurance. Problem: Available vaccines have limited efficacy. So, “outbreaks of whooping cough persist because transmission between individuals remains uninterrupted, despite high vaccination rates”, indicated an international research team led by Camille Locht, Inserm research director at the Lille Infection and Immunity Center.
Based on this observation, researchers have developed a new pertussis vaccine, called “BPZE1”. “This so-called ‘live attenuated’ vaccine (containing an attenuated version of the bacterium) has the particularity of being administered nasally and thus of mimicking the natural modes of transmission and colonization of Bordetella pertussis in the mucous membranes of the respiratory tract” , they explained in a statement.
280 people took part in the phase 2 clinical trial
To test the safety and effectiveness of this whooping cough treatment, scientists conducted a phase 2 clinical trial, the results of which have been published in the journal The Lancet. As part of this study, 280 Americans, aged 18 to 50, in good health were recruited and divided into two groups.
The first received a dose of BPZE1 nasally and a placebo intramuscularly. The members of the second group received an intramuscular injection of the so-called “acellular” dCaT vaccine, which does not contain complete bacteria but only certain proteins from Bordetella pertussis, and nasal placebo. Three months later, half of the volunteers in each of the two groups were given a dose of BPZE1, in order to simulate a natural infection in an attenuated way, while the other half received the intranasal placebo.
The nasal vaccine prevents bacterial colonization of the respiratory tract
According to the results, the new nasal vaccine induced consistent immunity in the nasal mucosa in addition to blood immunity. In addition, within 28 days of the second nasal administration, 90% of adults who initially received BPZE1 had no nasal bacterial colonies. “In the remaining 10%, colonization was low (less than 260 colonies per mL of mucus). In comparison, 70% of patients vaccinated with dCaT had significant nasal bacterial colonization (nearly 14,325 colonies per mL)”, can we read in the Inserm press release.
The authors also found that the infection regressed faster in participants vaccinated with the BPZE1 vaccine. “No serious adverse effects linked to vaccination” was reported in the study. “The benefit/risk profile of the BPZE1 vaccine is favorable: a single nasal administration makes it possible to induce, without danger and with good tolerance, strong and lasting immunity”, said Camille Locht. According to her, this vaccine could help break the chains of epidemic transmission of whooping cough.